Analysis of polymer oxidation using 18O2 and TOF-SIMS

We have investigated oxidative degradation of low density polyethylene (LDPE) by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Replacing O-16(2) in the exposure atmosphere by O-18(2) makes it possible to identify species originating from the artificial ageing, since oxygen present in the material prior to ageing can then be distinguished from oxygen introduced in the ageing process. The yield of O-ions in TOF-SIMS is very high, making oxygen-18 an excellent tool for following early stages of oxidative degradation. Furthermore, we have identified two O-18-containing ions, (CH3O+)-O-18 and (C2H3O+)-O-18, which can also be used to follow the oxidation processes. (C) 2003 Elsevier Science Ltd. All rights reserved.